The US on Thursday announced a huge new package of arms and munitions for Ukraine as the country's western supporters seek to boost its armoured forces.
The package does not feature western battle tanks requested by Kyiv, but does include 90 Stryker armoured personnel carriers, another 59 Bradley infantry fighting vehicles, Avenger air defence systems, and large and small munitions, the Pentagon said.
"The 59 Bradley IFVs included in this package, together with the 50 Bradleys previously committed on January 6 and the 90 Stryker APCs will provide Ukraine with two brigades of armored capability," it said.
An initial 50 Bradleys were included in a more than $3 billion package announced last week.
The US and other countries have made several large donations of armoured vehicles to Ukraine, but with the exception of Britain have not pledged to provide modern Western tanks.
Britain promised last weekend that it would send Challenger 2 tanks to Ukraine, while Germany said last week that it would provide Marder armoured vehicles, and France has promised to supply AMX-10 RC light tanks.
The US has said it is reluctant to provide its Abrams tanks to Ukraine because of difficulties with maintenance and training.
A senior US politician said German Chancellor Olaf Scholz told congressmen that Berlin would supply heavy tanks to Ukraine if the US did.
Although Germany has been cautious about providing heavy weapons, Mr Scholz is facing mounting pressure within Europe to authorise exports of German-made Leopard tanks.
Berlin left the door open to letting allies supply Ukraine with the tanks, saying late on Thursday it would "become clear in the next few hours or tomorrow morning."
The latest US package — which was announced the day before a major aid meeting in Germany — brings Washington's total military assistance to Ukraine since Russia's February invasion to more than $26.7 billion.